The β-glucan content of barley intended for use in beer production should be known.
The fluorochrome Calcofluor forms a complex with high molecular weight β-glucans (molecular weight greater than 5 kDa). Complex formation results in an increase in fluorescence; however, this fluorescence is extremely unstable due to photochemical degradation.
Through measurement in an automatic analysis system based on flow injection (flow-injection analysis, fig. 1), reproducible measurements for fluorescence and determination of β-glucan are possible. For barley analysis, it is necessary to use a short acid hydrolysis procedure to bring insoluble β-glucan into solution. The apparatus is calibrated using purified barley β-glucan standards.
Malt intended for use in beer brewing or elsewhere in the food industry.
This method is based upon on the fact that the β-glucan-rich cell walls of the endosperm are progressively broken down during malting. This process can be made visible by staining the cell walls that are still intact with the fluorochrome Calcofluor, which exclusively binds β-glucans starting at a molecular weight of approx. 10,000 D.
Modification is revealed by allowing the barley kernels, which have been cut in half, to react with Calcofluor (with Fast Green as a contrast medium). The kernels are subsequently examined under UV light (365 nm) in a suitable analyzer device. An intense, bright blue fluorescence occurs where unmodified endosperm cells are present, while the modified parts appear dark blue.
This method describes the fluorimetric determination of high-molecular weight β-glucans in malt.
Malt intended for use in beer brewing or elsewhere in the food industry
Fluorometric determination of high-molecular weight β-glucan
wort, beer
The fluorochrome Calcofluor forms a complex with high molecular weight β-glucans (molecular weight greater than 10,000 Da). Complex formation results in an increase in fluorescence; however, this fluorescence is extremely unstable due to photochemical degradation. Through measurement in an automatic analysis system based on flow injection (flow-injection analysis), reproducible measurements for fluorescence and determination of β-glucan are possible. The device is calibrated using standard solutions of purified β-glucan from barley.
The cations in beer and wort are determined with this analysis.
This method is suitable for both wort and beer.
Inductively coupled plasma optical emission spectroscopy (ICP-OES) is a fast and reliable method for the laboratory analysis of metals. Inductively coupled plasma (ICP), a high frequency field of ionized gas, serves as a medium for atomizing and exciting the substances found in samples. Liquid, dissolved or aerosol samples are injected into the ionized gas stream. In emission spectroscopy, ICP can be used in conjunction with a number of optical and electronic systems either simultaneously or sequentially in multi-element spectrometers. In the plasma, the atoms and ions are excited to a higher energy state bringing about the emission of electromagnetic radiation (light), primarily in the ultraviolet and visible region of the spectrum. Metals ordinarily occur as ions in the temperature range typical for ICP of 6000 to 10000 K; however, non-metals and metalloids are only partially ionized.
ICP-OES operates within a very wide range. This usually encompasses six orders of magnitude in concentrations smaller than μg/l up to g/l, depending upon the element and the concentrations used for the set of analysis data. With ICP-OES, beer and wort can also be analyzed without prior processing of the samples, in contrast to AAS. Methods for determining the following in beer and wort will be described below: Al, B, Ba, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, Si, Sr, Sn and Zn.